The effect of abscisic acid and benzylaminopurine on photosynthesis and transpiration rates of maize ( Zea mays L.) under water stress and subsequent rehydration

The young plants of maize were cultivated as sand culture under controlled conditions in a greenhouse. The water stress caused by interruption of irrigation for a period of 8 days had the effect of statistically significant decrease of the photosynthesis rate (P N ) and the transpiration rate (E) as compared with plants under no stress. When the plants were treated with a 100 μM abscisic acid (ABA) solution before the interruption of irrigation, this had the effect of further decrease of the levels of P N and E during the first period of measurement (3 to 4 days after interruption of irrigation) and the effect of slowing down the development of water stress in the following period (7 to 8 days after interruption of irrigation). ABA applied through irrigation was more effective than the one applied by sprinkling because it significantly increased the water use efficiency (WUE) in the treated plants. Benzylaminopurine (BAP) used as a 10 μM solution brought about an increase of P N and E in comparison with the plants under stress, not treated phytohormones. The result of the combined application of both growth regulators were steady levels of P N during the entire eight-day evaluation of water stress imposed on maize plants. However, during the second period of measuring, the higher levels of E were reflected in a decrease of the WUE level. Two days after irrigation was resumed, the subsequent saturation of plants with water was manifested by an increase of P N in all groups of plants under stress. However, the fairly steady levels remained below the level of P N measured in the control sample under no stress. Rehydration had various effects on E. The level of E increased the most in the case where ABA was used as irrigation. It also increased moderately in the case where ABA was applied by sprinkling and in the case of the plants under stress, not treated phytohormones. On the contrary, E stagnated in the cases with BAP and decreased in the cases where ABA and BAP were applied together

Metabolism of Pharmaceuticals in Plants and Their Associated Microbiota

With the increasing use of wastewater for irrigation of farmland, and thus the potential uptake and translocation of pharmaceuticals and their metabolites in crops, concerns about food safety are growing. After their uptake, plants are able to metabolize drugs to phase I, phase II, and phase III metabolites. Phase I reactions closely resemble those encountered in human drug metabolism, including oxidations, reductions, and hydrolysis. Phase II reactions, in turn, encompass conjugations with glutathione, carbohydrates, malonic acid, and amino acids. In phase III, these conjugates are transported and stored in the vacuole or bound to the cell wall. Pharmaceutical metabolism in plants has been investigated by using different approaches, namely, the use of whole plants grown in soil or hydroponic cultures, the use of plant tissues, and the incubation of specific plant cell suspensions. While studies relying on whole plants require long growth periods and more complex analytical procedures to isolate and detect metabolites, they constitute more realistic scenarios with the ability to determine site-specific metabolism and the translocation within the plant. The advantage of in vitro studies lies in their rapid setup. Recent advances in plant-microbiota investigations have shown that the plant microbiome modulates the response of the plant towards pharmaceuticals. Rhizospheric and endophytic bacteria can directly contribute to pharmaceutical metabolism and influence plant uptake and translocation of pharmaceuticals and their metabolites. Additionally, they can have beneficial properties for the host, contributing to plant health and fitness. This chapter gives an overview of human and plant drug metabolism followed by a comparison of different models used to identify pharmaceutical metabolites and their metabolic pathways in plants. A description of the mechanisms and reactions originating these metabolites is concisely presented. Finally, the role of the microbiome is critically discussed with examples of synergies between plants and their associated microbiota for pharmaceutical degradation.Peer reviewe

Incidence of hypo- and hyper-capnia in a cross-sectional European cohort of ventilated newborn infants.

Objective: To determine the incidence of hypo- and hyper-capnia in a European cohort of ventilated newborn infants. Design and setting: Two-point cross-sectional prospective study in 173 European neonatal intensive care units. Patients and methods: Patient characteristics, ventilator settings and measurements, and blood gas analyses were collected for endotracheally ventilated newborn infants on two separate dates. Results: A total of 1569 blood gas analyses were performed in 508 included patients with a mean±SD Pco2 of 48±12 mm Hg or 6.4±1.6 kPa (range 17-104 mm Hg or 2.3-13.9 kPa). Hypocapnia (Pco252 mm Hg or 7 kPa) was present in, respectively, 69 (4%) and 492 (31%) of the blood gases. Hypocapnia was most common in the first 3 days of life (7.3%) and hypercapnia after the first week of life (42.6%). Pco2 was significantly higher in preterm infants (49 mm Hg or 6.5 kPa) than term infants (43 mm Hg or 5.7 kPa) and significantly lower during pressure-limited ventilation (47 mm Hg or 6.3±1.6 kPa) compared with volume-targeted ventilation (51 mm Hg or 6.8±1.7 kPa) and high-frequency ventilation (50 mm Hg or 6.7±1.7 kPa). Conclusions: This study shows that hypocapnia is a relatively uncommon finding during neonatal ventilation. The higher incidence of hypercapnia may suggest that permissive hypercapnia has found its way into daily clinical practice